Abstract: To improve the muti-valve’s commutation ability and to reduce the valve’s flow forces during its opening， the valve structure of a hydraulic excavator under virtual loads was designed. First， the excavator virtual load model was established based on the excavator dynamic test data， and the statistics were used to express the load’s periodic and random characteristics. Then， a 3D valve model with the boundary conditions of virtual load was proposed to solve the flow forces during the valve’s opening using the fluid structure interaction method. Finally， the flow force response characteristics of different valve spool structures were presented by the model. The results show that the spool with U-groove of moderate equivalent valve orifice area can effectively reduce the flow force under a series of virtual loads.

Key words: commutation ability, virtual load, flow force, fluid-structure interaction, spool design